DIPTERA. 625 



The male orE;ans in some are accompanied by plate-like appendages. 



Ort/ior/iile, Latr., bas the proboscis forming a small beak. 



In the I'est the proboscis is shore, or scarcely prnminent. 



DoUchopns proper, has the third joint of the anteiiiiEc nearly triaiig:ular, but little elongated, with a seta of 

 moderate length, without a thickened knot between the middle and extremity. 



These insects are often of green or copper colours; the legs are long, and very delicate. Tbey station them- 

 selves on walls, the trunks of trees, leaves, &c. Some run with celerity on the surface of water. The male organs 

 of generation are always external, large, complicated, and folded beneath the abdomen. B. nngulnhts. Fab., the 

 larva of which lives in the earth : it is long, cylindric, with two points in form of two recurved hooks. The pQpa 

 has two curved horns in front of the thorax, 



^'^p/nstroma, Meig., has the last joint of the antennas nearly in the form of the blade of a knife, with a very long 

 seta, knotted beyond the middle. 



The male organs in the others are furnished with filiform appendages. In some the hind part of the antenna; is 

 either oval, triangular, or very long. 



Rhaphium, Meig., has it very long, and nearly lanceolate. 



Porphyrops, Meig., bas it hatchet-shaped or triangular, with a villose seta, the tirst joint of which is indistinct. 



Medctenis, Fisch., has the seta simple and dorsal, with the basal joint distinct and elongated, and the last joint 

 of the [intennai oval, 



Ilijdrophorus, Macq., differs from Medeterus in having the seta entirely terminal. 



In the others, the third joint of the autennEe is nearly globose, and the seta always villose. 



Chnjsotiis, has it terminal. 



PsUopifs, has it inserted rather above. 



D/ap/iuru^, has it inserted lower, and the head nearly spherical, and entirely occupied by the eyes, in the males, 

 thus appearing to conduct us to the next family, Plaii/pczincc. The wings, ocelli, and other characters derived 

 from the parts of the head, corroborate those which we have mentioned, but it is impossible for us to enter into 

 such details. 



The PlatypeziiiEe of Meigen, from -wliich Macquart has judiciously removed the genus Cyrtoma, and 

 to which we have added that of Scenopmus, and his family Megacepkali, is composed of Diptera very 

 similar in the proboscis, antennce, and wings to Dolichopus, but the body is depressed, with the head 

 licmispherical, and almost entirely occupied by the eyes, at least in the males. The legs are short, 

 without spines, and with the posterior tarsi often flat and broad. 



These Diptera are very small. Some of them have a seta in the last joint of the antennas. Thos^ 

 in wliich it is terminal, and the eyes contiguous above in the males, form two subgenera. 



Callomi/ia, Meig., has the basal joint alone of the posterior tarsi dilated, but as long as all the rest united. 



Plaiijpezay Meig., has the four basal joints of the posterior tarsi flattened. 



Pipnncnliis, Latr., {Cephalops, Fall.), bas the seta inserted on the back of the third joint, near its base; the 

 tarsi are not dilated, the eyes not united above in either sex, and the head nearly globose. 



iScenopinus, Latr., has no seta to the terminal joint of the antenna;, which is narrowei" and longer than in the 

 preceding. 



THE THIRD FAMILY OF THE DIPTERA,— 



The Tatjanides, — ■ 



Has, for its characters, a prohoscis exserted, and generally terminated by two lips ; with the palpi 



porrectcd, tlie last joint of the autennas annuLated, and a sucker of three pieces. It comprises the 



genus 



Tabanus, Linn.,— 



And is composed of large flies, well known for tlie torments they inflict upon horses and cows, of 

 wliich they pierce the skin, in order to suck their blood. The body is generally but slightly hairy; 

 the head is as wide as the thorax, nearly hemispherical, and covered, except in a narrow space, particu- 

 larly in the males, by the eyes, which are generally golden-green, with purple stripes. The antennae 

 are nearly as long as the head, 3-joiuted ; the last joint being terminated in a point without seta or 

 style at the tip, often notched at the l)ase above, with transverse divisions, in number from three to 

 seven. The proboscis in the greater number is nearly membranous, perpendicular, of the length of 

 the head or rather shorter, nearly cylindrical, and terminated by two elongated lips ; the two palpi 

 mostly rest upon it, and are thick, villose, conical, comiu-esstd, and 2-jointed ; the sucker, inclosed in 

 the proboscis, is comiutscd of six pieces like lancets, and which from their number and respective situ- 

 ation represent the parts of the mouth of the Coleoptera. [It is only the females which possess this 

 number of lancets ; the mouth of t!ie males is much weaker, and has only four. This sex is harmless, 



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